This work demonstrates techniques that advance the standard practice in spindle metrology and enable five degree-of-freedom calibration of precision spindles with nanometer-level error motion. Several improvements are described in this paper: (1) an improved implementation of Donaldson and Estler reversal that eliminates moving and realigning the displacement sensor, (2) frequency domain low-pass filtering of data to remove spectral content without distortion, (3) robust removal of low frequency components caused by thermal drift and fluctuations in air bearing supply pressure, and (4) three-dimensional display of the synchronous error motion in the radial and axial directions. Example measurements demonstrate the repeatability and reproducibility of the techniques. Furthermore, synchronous radial error motion of an air bearing spindle calibrated by multi-step, master artifact, and master axis techniques agree within 1 nm.

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A prototype spindle for low-force, low-speed applications that is kinematically constrained in accordance with the principles of exact constraint was designed, fabricated, and tested. In the prototype spindle, the position and orientation of the shaft (rotor) are constrained at five contact points; four constraints are arranged radially around the rotor, and one constraint is located at the end of the rotor. This paper describes the design of the prototype spindle and presents a study of its error motion for the hardened steel rotor sliding on brass and UHMW-PE bonded to ceramic. The error motion is observed to be highly repeatable with less than 100 nm asynchronous errors, and a simple analytical model enables the prediction of the synchronous error motion using measurements of the rotor's roundness profiles.

Articles you may be interested in 2D longitudinal modeling of heat transfer and fluid flow during multilayered direct laser metal deposition process J. Laser Appl. 24, 032008 (2012); 10.2351/1.4726445Investigation of surface and subsurface damage in diamond grinding of optical glass using hybrid copper-resinbonded diamond wheel Single crystal calcium fluoride ͑CaF 2 ͒ shows significant variation in material properties as a function of crystallographic orientation. The surfaces generated by material removal processes such as diamond turning are influenced by this anisotropy and consequently show periodic undulations aligned with the crystal structure. This article explores the relationship between surface figure and cutting forces measured during the diamond turning of single crystal calcium fluoride. The cutting forces, when mapped to the physical geometry of CaF 2 plano (flat) optics, show good correlation with surface figure measured by interferometry. A model is presented to predict the surface figure error from the experimentally measured normal component of the cutting force. The model also shows how the surface figure obtained under various machining parameters may be extrapolated from force measurements made during a single diamond turning operation.

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